#--
# Copyright (c) 2007-2008 Ryan Grove <ryan@wonko.com>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#   * Redistributions of source code must retain the above copyright notice,
#     this list of conditions and the following disclaimer.
#   * Redistributions in binary form must reproduce the above copyright notice,
#     this list of conditions and the following disclaimer in the documentation
#     and/or other materials provided with the distribution.
#   * Neither the name of this project nor the names of its contributors may be
#     used to endorse or promote products derived from this software without
#     specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#++

module Net
  class Flickr

    # Implements the Flickr authentication API. Please see
    # http://flickr.com/services/api/auth.spec.html for details on how to use this
    # API in your application.
    # 
    # Don't instantiate this class yourself. Instead, create an instance of the
    # +Flickr+ class and then user <tt>Flickr.auth</tt> to access this class,
    # like so:
    # 
    #   require 'net/flickr'
    #   
    #   flickr = Net::Flickr.new('524266cbd9d3c2xa2679fee8b337fip2',
    #       '835hae5d6j0sd47a')
    #   
    #   puts flickr.auth.url_desktop
    # 
    class Auth
      class << self
        PERM_NONE   = :none
        PERM_READ   = :read
        PERM_WRITE  = :write
        PERM_DELETE = :delete
  
        attr_reader :frob, :perms, :user_id, :user_name, :user_fullname
    
        # allows the token to be set if its already been fetched and stored
        # in a database or flat file
        attr_accessor :token
    
        def initialize
          @frob          = nil
          @perms         = PERM_NONE
          @token         = nil
          @user_id       = nil
          @user_name     = nil
          @user_fullname = nil
        end
    
        #--
        # Public Instance Methods
        #++
    
        # Updates this Auth object with the credentials attached to the specified
        # authentication _token_. If the _token_ is not valid, an APIError will be
        # raised.
        def check_token(token = @token)
          update_auth(Net::Flickr.request('flickr.auth.checkToken', 'auth_token' => token))
          true
        end
    
        # Gets the full authentication token for the specified _mini_token_.
        def full_token(mini_token)
          update_auth(Net::Flickr.request('flickr.auth.getFullToken', 'mini_token' => mini_token))
          @token
        end
    
        # Gets a frob to be used during authentication.
        def get_frob
          @frob = Net::Flickr.request('flickr.auth.getFrob').at('frob').content
        end
  
        # Updates this Auth object with the credentials for the specified _frob_ and
        # returns an auth token. If the _frob_ is not valid, an APIError will be
        # raised.
        def get_token(frob = @frob)
          update_auth(Net::Flickr.request('flickr.auth.getToken', 'frob' => frob))
          @token
        end
    
        # Gets a signed URL that can by used by a desktop application to show the
        # user a Flickr authentication screen. Once the user has visited this URL
        # and authorized your application, you can call get_token to authenticate.
        def url_desktop(perms = :read)
          get_frob if @frob.nil?
          Net::Flickr.connection.sign_url(Net::Flickr::Connection::AUTH_URL + "?api_key=#{Net::Flickr.connection.key}&perms=#{perms}&frob=#{@frob}")
        end
    
        # Gets a signed URL that can be used by a web application to show the user a
        # Flickr authentication screen. Once the user has visited this URL and
        # authorized your application, you can call get_token with the frob provided
        # by Flickr to authenticate.
        def url_webapp(perms = :read)
          Net::Flickr.connection.sign_url(Net::Flickr::Connection::AUTH_URL + "?api_key=#{Net::Flickr.connection.key}&perms=#{perms}")
        end
    
        #--
        # Private Instance Methods
        #++
    
        private
    
        # Updates this Auth object with the credentials in the specified XML
        # _response_.
        def update_auth(response)
          auth = response.at('auth')
          user = auth.at('user')
      
          @perms         = auth.at('perms').inner_text.to_sym
          @token         = auth.at('token').inner_text
          @user_id       = user['nsid']
          @user_name     = user['username']
          @user_fullname = user['fullname']
        end
      
      end
    end
  end
end